The subject matter disclosed herein relates to turbines and, more particularly, to systems and devices for shielding conduit surfaces in a turbine and reducing thermal gradients within turbine components.
Some power plant systems, for example certain nuclear, simple cycle and combined cycle power plant systems, employ turbines in their design and operation. Some of these turbines (e.g., gas turbines) include conduits (e.g., routing holes, cooling holes, etc.) which route fluids about and within components of the turbine. During operation, as these conduits redirect portions of the working fluid, the materials and components which comprise these conduits may become thermally stressed and/or exposed to turbulent fluid conditions (e.g., during start-up, cool-down, or shut down). As the working fluid flow contacts these components, thermal gradients may develop across component regions, causing differential expansion, cracking, and wear. For example, the heat transfer coefficient at an exposed edge of a conduit may vary significantly relative to the heat transfer coefficient at an internal portion of the conduit. This variance in the heat transfer coefficient may develop thermal gradients which impart thermal stresses, damage components, decrease efficiency, shorten component lifespan, and limit turbine design options.
Referring to FIG. 1, a schematic partial cross sectional view of a portion of a turbine 100 is shown including a turbine component 102. Turbine 100 illustrated in FIG. 1 may include a component conduit 110 formed in turbine component 102. During operation a working fluid flow ‘F’ may contact turbine component 102 and/or component conduit 110. Component conduit 110 may direct a cooling portion ‘C’ of working fluid flow F into turbine component 102 and about turbine 100. A first surface 132 of component conduit 110 proximate working fluid flow F may be exposed to a high degree of turbulence and thermal variation relative a second surface 134 of component conduit 110 disposed within turbine component 102. This variance in turbulence and thermal exposure may cause thermal stresses, component damage and inefficient operation.